Getting arrested and charged with drug possession will be certain to debar him entry to the US. The first thing you would need to get done is lawyer-up and get his name cleared. Once that is sorted out, he can think of entering the US and pursuing higher studies.

This Forum will not be able to provide you legal advise. Please consult Attorney's at Murthy Law Firm. Also, apparently you do not want to divorce your wife, in which case, why don't you settle this issue amicably (unless of course your wife is seeking divorce)?

You should have provided details of the arrest to USCIS and also the fact that the case was expunged. Failure to disclose any arrest is viewed as concealment of facts. That in itself may provide grounds for denial of renewal.

While filing for OCI you will be asked about the name change and have to provide documentary evidence for that. It should not cause any legal complications since a number of people of Indian Origin do a name change while naturalizing and the Indian government is aware of this.

Haha, I have been In-Line for interview since December 7th, 2016. Depends on your FO how long the wait period is. Mine at Memphis TN is terribly backlogged. You could ring up the helpline and ask what the status is and they will tell you exactly what you can see on the processing times available online for various FO's. Not much help. If after 6-8 months there is still no progress, make an infopass. I am considering an Infopass, since I am at 233 days past filing.

@Ashley 2017: There are Application support centers (Where they do the Biometrics) and then there are Field Offices which conduct interviews. Depending on the county you are located in, you will have either one FO or more than one (as in my case). Depends to which of these FO's the N400 is sent from where you filed it (Dallas, Texas etc). Some FO's conduct both interview and oath ceremony the same day, others do it on different scheduled dates and times. Processing time can be found here:
https://egov.uscis.gov/cris/processTimesDisplayInit.do

@Ashley 2017. I never had any traffic violations, so I did not have to attach any documentation. I looked up the processing times as provided by the USCIS website https://egov.uscis.gov/cris/processTimesDisplayInit.do
Look up your FO from the drop down menu and look up the processing time for N400.

I applied in November 2016, A couple of days after my Biometrics in December 2016 (December 7th) i was placed "Inline for interview scheduling". Yet to get an update after that or the interview letter. I guess it depends on the processing time of the USCIS FO. I looked up mine and found they were still processing April 2016. So one just has to sit tight...if the case is "In-line for interview scheduling", one can assume the BC is over..